Polythiophenes have been studied extensively due to their interesting electrical and/or optical properties. Polythiophenes become electrically conducting upon chemical or electrochemical oxidation or reduction.
EP-A 339 340 discloses a polythiophene containing structural units of the formula:
in which A denotes an optionally substituted C1-4-alkylene radical and its preparation by oxidative polymerization of the corresponding thiophene.
EP-A 440 957 discloses dispersions of polythiophenes, constructed from structural units of formula (I):
in which R1 and R2 independently of one another represent hydrogen or a C1-4-alkyl group or together form an optionally substituted C1-4-alkylene residue, in the presence of polyanions.
EP-A 686 662 discloses mixtures of A) neutral polythiophenes with the repeating structural unit of formula (I),
in which R1 and R2 independently of one another represent hydrogen or a C1-C4 alkyl group or together represent an optionally substituted C1-C4 alkylene residue, preferably an optionally with alkyl group substituted methylene, an optionally with C1-C12-alkyl or phenyl group substituted 1,2-ethylene residue or a 1,2-cyclohexene residue, and B) a di- or polyhydroxy- and/or carboxy groups or amide or lactam group containing organic compound; and conductive coatings therefrom which are tempered to increase their resistance preferably to <300 ohm/square. Examples of di- and polyhydroxy organic compounds disclosed in EP-A 0 686 662 are: sugar and sugar derivatives, such as saccharose, glucose, fructose, lactose, sugar alcohols, such as sorbitol and mannitol, and alcohols such as ethylene glycol, glycerine, diethylene glycol and triethylene glycol.
U.S. Pat. No. 5,427,841 discloses a laminated structure comprising an electrically insulating substrate carrying a polymer layer consisting essentially of a polymer selected from the group of poly-3,4-ethylene dioxythiophene, poly(3,4-ethylene dioxythiophene) wherein the ethylene group is substituted with a C1-C12 alkyl group, poly(3,4-ethylene dioxythiophene) wherein the ethylene group is substituted with an alkoxy group, and oligomers of ethylene dioxythiophene, said layer having first electrically conductive portions having a sheet resistance of maximally 1000 Ω/square, and a pattern of second substantially non-conductive portions whose sheet resistance is at least a factor of 106 higher than that of the conductive polymer in said first portions, a metal layer being deposited into the electrically conductive first portions of said polymer layer. U.S. Pat. No. 5,427,841 also discloses a room temperature stable spin coating solution which comprises a substance selected from the group of monomers, oligomers and polymers selectively polymerizable (a) to an electrically conductive polymer having a sheet resistance of maximally 1000 Ω/square; (b) to an electrically non-conductive polymer; and (c) to a polymer having conductive and non-conductive areas; said solution further including an oxidation agent; a base (e.g. imidazole); and a solvent.
U.S. Pat. No. 5,447,824 discloses a method of manufacturing a pattern of an electrically conductive polymer on a substrate surface, said method comprising: a) forming a liquid layer on a surface of said substrate from a solution containing a material capable of forming said electrically conductive polymer upon being heated, an oxidizing agent and a base (e.g. imidazole), b) exposing said liquid layer to patterned radiation, and c) heating said layer thereby forming a pattern of an electrically conductive polymer, said conductive polymer being formed in unexposed areas and a non-conductive polymer being formed in the exposed areas of the layer.
U.S. Pat. No. 5,620,800 discloses a method of manufacturing a laminated structure having an electrically insulating substrate carrying a polymer layer comprising first electrically conductive portions having a sheet resistance of maximally 1000 Ω/square and a pattern of second relatively substantially non-conductive portions when the sheet resistance of the polymer in the first portions is compared to the sheet resistance of the polymer in the second portions, a metal layer being electrodeposited onto the electrically conductive first portions of said polymer layer, said method comprising the steps of: providing a layer of a solution comprising 3,4-ethylene dioxythiophene monomers, an oxidation agent, a base (e.g. imidazole) and a solvent on the substrate, exposing the layer to patterned radiation, heating said exposed layer thereby forming conductive polymer areas in the unexposed areas and said substantially non-conductive polymer areas in the exposed areas, and thereafter electrodepositing a metal layer selectively onto the conductive polymer from a metal salt solution.
US 2006/0076541A discloses a conductive composition comprising: a π-conjugated conductive polymer, a polyanion, and a hydroxy group-containing aromatic compound containing two or more hydroxy groups. In a preferred embodiment the polyhydroxyl group-containing aromatic compound is represented by formula (1):
wherein R represents a group selected from a linear or branched alkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, or an aralkyl group, each having 1 to 15 carbon atoms. In a further preferred embodiment the hydroxy group-containing aromatic compound contains a sulfo group and/or a carboxy group. The invention examples of US 2006/0076541A demonstrate conductivity enhancement upon addition of a hydroxy group-containing aromatic compound containing two or more hydroxy groups and enhanced heat stability and humidity stability of the electrical conductivity.
JP 2006-291133A1 discloses a conductive polymeric coating material contains a π-conjugated conductive polymer, a polyanion, an ester compound, and a solvent, the ester compound being a dehydration reaction product of a carboxylic acid compound having at least two carboxyl groups and a polyhydric alcohol compound having at least two hydroxyl groups. The method for producing the coating material comprises an ester compound synthesis process for synthesizing the ester compound by the dehydration reaction of the carboxylic acid compound having at least two carboxyl groups and the polyhydric alcohol compound having at least two hydroxyl groups and an ester compound addition process for adding the ester compound to a solution or dispersion containing the π-conjugated conductive polymer, the polyanion, and the solvent.
JP 2006-321840A discloses an electrically conductive polymer solution comprising a π-conjugated conductive polymer, a polyanion, a nitrogen-containing compound and a solvent, the nitrogen-containing compound having one or more nitrogen-containing functional groups selected from urea group, urethane group, allophanate group, biuret group, imide group and amide group, wherein the nitrogen atom of the nitrogen-containing functional group has the form of quaternarized salt, the nitrogen-containing compound of the conductive polymer solution preferably having one or more unsaturated double bonds. The conductive coating film is produced by coating the conductive polymer solution.
JP 2006-328276A1 discloses an electrically conductive polymer solution comprises a π-conjugated electrically conductive polymer, a solubilizing polymer, an amide compound and a solvent. The electrically conductive coating film is such as to be formed by coating the above polymer solution.
A general drawback of electroconductive layers containing poly(3,4-dialkoxythiophene) polymers, a polyanion and a hydroxy group-containing aromatic compound containing two or more hydroxy groups is the low electrical conductivity and the prohibitive increase in their surface resistance upon exposure to visible and UV light.
A general drawback of electroconductive layers containing poly(3,4-dialkoxythiophene) polymers and a polyanion with conductivity enhanced by contact with high boiling point liquids such as di- or polyhydroxy- and/or carboxy groups or amide or lactam group containing organic compound optionally followed by heating at elevated temperature is the rapid increase in their surface resistance upon exposure to visible and UV light.